Container of pineapple sherbet
bag of frozen blackberries
Keep the blackberries frozen but soften the pineapple and throw in a larger bowl (that has a cover and will fit in your freezer). slice/dice the banana into the sherbet add the blackberries stir and refreeze. Serve. If you want to get fancy add one of those fancy, expensive, thin cookies by Jules Destrooper that I use in a great Lemon 'ice cream' bar blogged about earlier here.
Have you ever heard of an easier dessert? It's delish and doesn't heat up the kitchen.
edit; I just made a batch and 2 bananas look like enough. I used a potato masher to initially smush and stir up the sherbet; then used a spoon to gently stir the 1/4-1/2 slices of banana and then added the blackberries.
Jeanne asked if you could use fresh blackberries...sure you can but freeze them first so they don't get smashed when you stir the sherbet.